Flexographic printer with enclosures at a regulated temperature and vapor extraction

ABSTRACT

The invention relates to a flexographic printer comprising: inner dividing means which, together with a surround casing, define first, second and third enclosures; and fluid circulation means which are used for the circulation of at least one fluid at a regulated temperature. The aforementioned enclosures are sufficiently closed off and insulated from one another and the fluid is circulated at a sufficient flow rate, such that the solvent vapour concentration in the atmosphere, originating from the ink, is below a lower pre-fixed explosion limit in at least the second and third enclosures which house means of actuating the rotation and movement of the cylinders and electric and/or electronic devices and/or elements associated therewith.

This application is a U.S. National Phase Application of PCTInternational Application PCT/ES02/00135, filed Mar. 20, 2002.

TECHNICAL FIELD

This invention concerns a flexographic printer withtemperature-regulated sections and vapour extraction, and morespecifically, a flexographic printer including a casing fitted withinterior means of division that form suitably insulated sectionscontaining various printer components, with a fluid at a regulatedtemperature circulating through these sections.

BACKGROUND

A flexographic printing machine typically consists of support structureson which one or more back-pressure cylinders are mounted, which supporta moving continuous band of material to be printed, and one or moreflexographic printing heads, each of which consists of a cliché-holdercylinder that can make contact with the cited band to be printed and anink-well or inking unit, which includes at least one ink cylinder tosupply ink to the cliché-holder cylinder. Each print head can beassociated with its respective back-pressure cylinder having arelatively small diameter or all the print heads can be located around asingle, central, large diameter back-pressure cylinder. Theincorporation of several print heads is employed to successively printthe continuous band in different colours. In this way, the first printhead deposits ink of one colour on the band to be printed and thesuccessive heads superimpose inks of other colours. To prevent colourmixing it is necessary to dry the previous colour ink before applyinganother. Drying the ink involves the evaporation of the pigment diluentit contains and this is usually accomplished using drying boxes locatedbetween the print heads, which include the means of blowing hot air ontothe printed band, together with the option of air suction to extract theair contaminated with the solvent vapour from the area of influence ofthe drying box.

It is also usual to protect this type of printing machine with casing orfairings that basically meet certain safety functions, preventingoperator access to dangerous components and health functions by reducingthe level of noise reaching the operators and also improving themachine's visual aspect. In order to comply with the cited soundproofingfunction, the fairings tend towards greater levels of insulation andsealing, with the acoustic insulation also doubling as heat insulation.

Unfortunately, this combination of insulation and sealing also involvesthe following two disadvantages:

-   -   The heating of all the machine's components because of the        heated air blown inside the casing by the drying boxes, and    -   A concentration of solvent vapour inside the casing,        specifically the lower section since typical solvent vapour is        denser than air.

The heating problem generally affects all the printer components andmechanisms, but very specifically the large-diameter centralback-pressure cylinder and its support structures, in those machinesfitted with them. This central back-pressure cylinder must bemanufactured with certain dimensional tolerances, especiallycylindricity, which are very close and must be maintained throughoutoperation periods. Because the drying boxes produce the hot airimpulsion directly over localised areas of the back-pressure cylinder,cylinder expansion, especially when operating slowly, can producedeformation that exceed the permitted tolerance. The expansiondeformation suffered by the support structures also negatively affectsthe machine's operation.

There are various well-known devices for cooling or maintaining theback-pressure cylinder at a constant temperature by means of circulatingwater. One such device consists of fitting the cylinder with a doublesteel wall that provides an intermediate space through which the coolingwater is able to circulate.

U.S. Pat. No. 5,048,418 describes a flexographic printing machine withsupport structures or beds fitted with the means to regulate thetemperature. These means consist of one or more closed channels for thecirculation of a cooling or temperature-regulating fluid. The channelsfollow spiral paths to cover at least the support structure zones wherethe back-pressure cylinder is mounted.

However, both the cited means for cooling the cylinder and the means ofcooling the support structure or bed are designed for very specificareas of the machine, but do not provide any overall temperatureregulation inside the casing.

With respect to the problem of solvent vapour concentration, thepreviously described means of extraction associated with the dryingboxes are known, but they are not sufficient to prevent an accumulationof solvent vapour of the lower section inside the insulated casing. Thevapour produced by commonly used solvents is highly inflammable andaccumulations inside the casing normally exceed a determined lowerexplosion limit, which means that a high-level of intrinsic protectionmust be employed in the printer's electrical devices and components, themeasurements of which are strictly regulated by industrial codes in mostcountries. The implementation of the cited means of high-levelprotection and safety involves high economic costs of the componentsand, in addition, does not reduce the concentration of the explosivevapours inside the casing.

The objective of this invention is to produce a flexographic printerwith a surrounding casing and interior dividing means in order toproduce at least two sections, fitted with the means to regulate thetemperature and the vapour concentration levels inside the casing thatare capable of providing a suitable operating temperature for thecomponent parts and, at least in one of the described section, the onehousing all the drive means and electrical or electronic devices,maintain a vapour concentration level below a preset lower explosionlimit, which will make the application of the high-level means ofprotection unnecessary for the described electrical devices.

Another objective of this invention is to provide a flexographic printerwith the additional advantage of protecting those elements associatedthe drives from dirt and to permit access for ease of cleaning in thoseareas exposed to possible impregnation by ink.

DESCRIPTION OF THE INVENTION

The previous objective is achieved in accordance with this invention, byproducing a flexographic printer of the type consisting of a frame onwhich are mounted at least one rotating back-pressure cylinder and atleast one print head, which consists of a cliché-holder cylinder thatcan make contact with a band to be printed supported on the citedback-pressure cylinder and an inking unit, consisting of at least oneinking cylinder that supplies ink to the cited cliché-holder from atank. The rotation of the various is provided by suitable drive means,generally electric motors. The components of the flexographic print headcan be moved closer to or farther away from the cited back-pressurecylinder, so that the machine is also fitted with the means of drivingthis movement the said components, which is also usually provided byelectric motors. The printer of this invention is also the type thatincludes the means for drying or curing the film of ink deposited on theband to be printed and a surrounding casing. The flexographic printer ofthis invention is characterised in that the cited surrounding casing, incombination with interior dividing means, delimits at least twosections, through which at least one fluid circulates that is introducedat a temperature regulated by a means of impulsion and is sucked out bymeans of extraction, with the cited sections being sufficiently closedto provide a specific atmosphere inside at an efficient controlledtemperature.

In addition, in one of the said sections, those printer organs thatproduce a continuous degree of solvent vapour generation areconcentrated, such as the inking cylinders, ink tanks and other inkercomponents etc, while those printer devices that contain electricaland/or electronic elements, such as drive motors, power supplies andcontrol etc, are concentrated in the other section, of which there is atleast one. Both sections are sufficiently insulated from each other sothat the degree of solvent vapour leakage from the first to the secondis secondary, with the circulating volume of the said fluid beingsufficient for the interior atmosphere of at least the second sectionthat houses the electrical and/or electronic components has a vapourconcentration from the ink that is below a lower preset explosion limit.This lower explosion limit is established in accordance with strictregulations in most countries or, in the absence of this, it may becalculated.

The fluid circulating through the cited sections should be a gas; morespecifically it should be air.

According to a preferred exemplary embodiment of the invention, thecited back-pressure cylinders, cliché-holder and inker are arrangedbetween the first and second support structures which make up the citedframe, while the cited means of rotation drive and movement are arrangedon the outer sides of both the first and second support structures. Thecited means of division are arranged in relation to the first and secondsupport structures in order to create three of the said separatedsections in co-operation with the surrounding casing: a first sectionbetween the first and second support structures, where the cylinders andcited means of drying are housed; and the second and third sections inexterior zones of the first and second support structures, where themeans of rotation drive and movement are housed. However, the inventionalso contemplates the possibility of arranging the means of division inrelation to only one of the support structures so that only two sectionsare formed: a first section between the first and second supportstructures, where the cylinders and means of drying are housed; and asecond section in an exterior zone of the first support structure, wherethe means of rotation drive and movement are housed. The essential part,in both cases, is that the first section houses the all the elementsthat are in direct contact with the ink and, therefore, where continuousevaporation of the solvent takes place, is sufficiently isolated fromthe second and/or third section where all the means of drive areconcentrated (in general, the electric motors) and electrical and/orelectronic components associated with the said means of drive, such asconnectors, switches, relays and fuses etc. Thus, in the first section,the risk of explosion is practically eliminated thanks to the mentionedair circulation, which guarantees that the said solvent vapourconcentration is maintained below the preset lower explosion limit,which will also avoid the need to install costly, high-level protectiondevices for the electrical elements whish would otherwise be necessary.

In addition to the actual motors and as is usual in this type ofmachine, the means of drive include also includes the means of guidanceand mechanical transmission, which here, are arranged in the said secondand third sections, and therefore safeguarded from possible inkimpregnations, with the said first section, together with the componentsit contains, being easily accessible for cleaning.

The mentioned means of air flow impulsion consists of at least one fanconnected to a conduit for the entry of the fluid, which is fitted withbranches with various impulsion mouths distributed inside the saidfirst, second and third sections. The mentioned means of extractionconsists of at least one fan connected to a fluid exit conduit fittedwith branches with various suction connections that are similarlydistributed inside the first, second and third sections. Because it isnormal to employ a solvent for the ink, the vapour of which is denserthan air, at least one of the said suction connections is located in thelower zones of the first section, which contains the cylinders and meansof drying, in order to extract the solvent vapour coming from the inkdrying and evaporation, together with the exiting fluid or air.

Just as was described earlier, the flexographic print head or heads canbe moved closer to or farther away from the back-pressure cylinder, ofwhich there is at least one. Thus, the cited components are mounted in amovable fashion on suitable guides fixed on the support structures.Since the cliché-holder cylinders are arranged in the first sectionbetween the support structures and their respective means of rotationdrive and movement are located in the second and third sections arrangedon the other sides of the support structures, these support structurescontain apertures by which part of the means of drive for theflexographic print head components are moved.

According to a construction example of this invention, the means ofdivision consist of curtains of fluid, in other words, air, driven fromimpulsion mouths connected to branches of the cited air entry conduitand located in relation to the said first and second support structuresin the upper section inside the casing. These curtains are sucked fromseveral of the said suction connections, which are connected to branchesof the exit conduit and located in a lower zone of the casing. Accordingto another construction example, the support structures from closedpanels in which the only apertures are those previously described above,by which the flexographic print head components are moved, and the meansof division consist of elastic and/or flexible and/or sliding elementsthat cover the cited apertures. It must be pointed out here that bothconstruction examples are fully compatible and can exist in the sameprinter design. It is not necessary for the casing and the means ofdivision to provide a complete seal for the sections, but that they aresufficiently closed in order to guarantee their intended purposes.

Conventional drying boxes may be employed for the means of drying orcutting, which are connected here by one side to specific means ofimpulsion, which blow previously heated air over the printed band and bythe other side to a branch of the cited exit conduit connected to thesaid means of general casing suction in order to suck the air andsolvent vapour from the ink.

The air from the drying box is heated by some means of heating, such asa fuel burner or electric element. The air that enters the sections at aregulated temperature via the entry conduit is heated/cooled by meansof, for example, a water/air heat exchanger located outside thesections.

As an advantage, the operation of the said heat exchanger unit and/orblower fan and/or extraction fan for regulating the entry flow rate andfluid flow rate and exit solvent vapour are controlled by certainelectronic means of control in function of a signal received from atleast one temperature sensor located inside the surrounding casing. Thetemperature regulation control is further completed by means of the saidtemperature sensors installed at various points in the said first,second and third sections, together with various means of registerdriven by their respective means of drive in various branches of thesaid entry and/or exit conduits. In this case, the cited electronicmeans also control the operation of the cited means of drive for themeans of register in order to regulate the flow rate and temperature ofthe entry fluid and fluid flow rate and exit solvent vapour in differentzones of the various sections in function of the signals received fromthe said various temperature sensors.

The printer configuration of this invention can consist of eitherseveral flexographic heads associated with a single common back-pressurecylinder, or several flexographic heads, each associated with its ownback-pressure cylinder. When there is only one common back-pressurecylinder, this may be optionally fitted with any of the knowntemperature regulation devices, such as the water cooling devicedescribed above.

BRIEF EXPLANATION OF THE DRAWINGS

The characteristics and advantages of this invention are made moreevident by the following detailed description of a preferredconstruction example with reference to the attached drawings, in which:

FIGS. 1A and 1B are simplified elevation and plan views respectively ofa flexographic printer in the prior art;

FIG. 2 is a simplified front elevation of the flexographic printer ofthis invention, in which the separated sections are shown that house thecylinders and means of drive respectively and in which the entry andexit conduits have been omitted for greater clarity of the drawing;

FIG. 3 is a perspective view, with certain parts of the flexographicprinter of this invention partially sectioned, in which the separatedsections and the entry and exit fluid conduits can be seen and in whichthe print heads have been omitted from greater clarity of the drawing;

FIG. 4 is a partial enlarged perspective view that shows certain detailsof the printer of this invention with relation to the support structuresthat form the frame.

DETAILED DESCRIPTION OF THE INVENTION

First referring to FIG. 2, this shows a example of the execution of theflexographic printer, which consists of a frame that defines the twosupports structures 1 a and 1 b, between which is a single, largediameter, back-pressure cylinder 2 that is mounted rotationally on thesaid frame 1 and fitted with an exterior support surface for a band tobe printed (not shown). This single, large diameter cylinder can becooled by means of a known water-cooled device. Several flexographicprinting heads are arranged in relation to the cited singleback-pressure cylinder 2, with each print head consisting of acliché-holder cylinder 4 that can make contact with the cited band to beprinted on the said back-pressure cylinder 2 and an inker unit, which ismade up of an inking cylinder 5 for supplying ink from tank to the saidcliché-holder cylinder 4. Although in the shown construction example,there is a single back-pressure cylinder 2, this invention could alsoapply to a printer (not shown) fitted with multiple, small diameter,back-pressure cylinders, each one being associated with a print head. Inany case, the components of the said flexographic print head can bemoved closer to or father away from the back-pressure cylinder. Each ofcylinders 2, 4 and 5 are coupled to the means of rotation drive 9 andthe flexographic print head components are also connected to the meansof movement drive. The printer include means for drying or curing thefilm of ink deposited on the band to be printed and surrounding casing6.

The essential characteristic this invention is that the citedsurrounding casing 6, in combination with interior dividing means 11,delimits at least two sections and, in general, three sections,designated here as the first, second and third sections 12 a, 12 b and12 c through which at least one fluid circulates that is introduced at atemperature regulated by a means of impulsion 21 and is sucked out bymeans of extraction 8 by suction (FIG. 3). The mentioned first, secondand third sections 12 a, 12 b and 12 c are sufficiently closed andinsulated from each other and the cited fluid circulation is carried outat a flow rate that is sufficient to provide an atmosphere with asolvent vapour concentration from the ink below a lower preset explosionlimit in at least the second section 12 b and, in general, in the secondand third sections 12 b and 12 c, which house certain electrical and/orelectronic elements and/or devices associated with the said means ofdrive (9, 10). The fluid circulation at regulated temperature alsomaintains most of the various printer components at a suitable operatingtemperature.

Preferably, the cited fluid is a gas and more preferably is air,although other gases, such as nitrogen, may also be employed.

As an advantage, the cited back-pressure cylinders, cliché-holder andinker 2, 4 and 5 and the said means of drying are installed betweencertain respective internal facing faces of the cited first and secondsupport structures 1 a and 1 b of the said frame 1, while the citedmeans of rotation drive 9 and 10 are arranged on respective externalfaces, opposite the cited facing faces of both the first and secondsupport structures 1 a and 1 b.

Just as will be explained below, with reference to FIGS. 3 and 4, inrelation to the first and second support structures 1 a and 1 b, thementioned means of division 11 are arranged to create three separatedsections: a first section 12 a between the internal facing faces of thefirst and second support structures 1 a and 1 b, which contain thecylinders 2, 4 and 5, together with the means of drying; and the secondand third sections 12 b and 12 c in zones adjacent to the said externalfaces of the first and second support structures 1 a and 1 b where themeans of rotation drive 9 and movement 9 and 10 are housed. In theexample shown in FIG. 2, the print heads are located above theback-pressure cylinder rotation 2 of shaft 2 a, with the means ofrotation drive in the third section 12 c and the means of movement drive10 in the second section 12 b. However, there may be print heads on bothsides of shaft 2 a and the means of rotation drive 9 and 10 may beinverted in sections 12 b and 12 c, alternatively distributed in boththe second and third sections 12 b and 12 c or all concentrated in thesame section, for example, in the second section 12 b. In this lattercase, the means of division 11 associated with the second supportstructure 1 b may be omitted so that there are only the first and secondsections 12 a and 12 b.

The purpose of the separated sections 12 a, 12 b and 12 c is to isolatezone 12 a in which the cylinders are located and consequently where theink is handled, of zones 12 b and 12 c where the cylinder drive meansare located, including the electric motors, and the electrical and/orelectronic components and devices associated with the said drive means.In addition, this separation also provide increased guarantees that inthe said zone, which houses the electrical and/or electronic componentsand devices, in other words, the second and/or third sections 12 b and12 c, the cited solvent vapour concentration is below the said presetlower explosion limit. This is achieved by means of the cited aircirculation at the regulated temperature, which also guarantees asuitable operational temperature in all sections 12 a, 12 b and 12 c.

As an additional advantage, it must be mentioned that the drive means 9and 10 include, in addition to the motors and power supply and controldevices, the means for guidance and mechanical transmission which, inthe printer of this invention, are also installed in the said second andthird sections 12 b and 12 c. In this way, all the elements andmechanisms associated with the drive means 9 and 10 are safeguarded frompossible impregnation by ink, with the first section 12 a and theelements it contains being easily accessible for cleaning.

If we briefly examine FIGS. 1A and 1B, which show a prior art printer,in which a frame 101 can be seen, consisting of support structures 101 aand 101 b, between which the back-pressure cylinder 102 and print unitcylinders 104, 105, together with their drive means, are mounted. Theassembly is closed by the surrounding casing 106. However, there is nocompartmentalisation inside the casing 106, which defines differentsections for the components that are in contact with the ink and for theelectrical components. In this prior art printer, the means of coolingare provided for cooling certain parts of the support structures 101 a,101 b and form the frame 101 by water circulation. However, the means toregulate the overall temperature inside the casing 106 are not provided.

Just as shown in FIG. 3, the mentioned means for circulating air consistof a fan 21, connected to an air entry conduit 13, which is fitted withbranches with various impulsion mouths 16 distributed inside the saidfirst, second and third sections 12 a, 12 b and 12 c. The said means ofextraction consists of a fan 8, connected to a air exit conduit 14,which is fitted with branches with various suction connections 17distributed inside the first, second and third sections 12 a, 12 b and12 c. In order to extract solvent vapour from the ink, together with theexit air, at least one of the said suction connections 17 a is arrangedin a lower zone of the first section 12 a.

According to the preferred construction example shown in FIG. 3, thesaid means of division 11 consists of air curtains at a regulatedtemperature blown from impulsion mouths 16 a, 16 b and 16 c, which areconnected to branches of the entry conduit 13 and located next to bothsides of the said first and second support structures 1 a and 1 b, inthe upper part of the inside of casing 6. Several suction connections 17a, 17 b and 17 c connected to the exit conduit branches 14 and locatednext to both sides of the first and second support structures 1 a and 1b in a lower zone of casing 6 suck the cited air curtains. Thus, anysolvent vapour attempting to escape from the first section 12 a, will bedragged by the air curtain turbulence and sucked out by the suctionmouths 17 a, 17 b and 17 c, together with the circulation air towardsthe exit conduit 14. This air mixed with solvent vapour may be processedin order to clean it and even to recover solvent before being releasedinto the atmosphere.

Now, in relation to FIG. 4, this shows another construction example, inwhich the said means of division 11 consist of, in cooperation with theactual support structures 1 a and 1 b, which have a configuration in theform of a panel, with apertures by which the flexographic print headcomponents move, sliding means 11 to cover these apertures as the saidcomponents move. These means of division may be elastic and/or flexibleelements, such as bellows, with the same efficiency. A more efficientcompartmentalisation may be achieved by jointly employing the aircurtains shown in FIG. 3 and the elastic or flexible sliding elements11, shown in FIG. 4.

The mentioned means of drying or curing consist of conventional dryingboxes 19, which are connected by one side to the means of air impulsiondirected towards the printed band and by the other side to at least onebranch of the cited exit conduit 14 connected to the said means ofsuction 8 to suck the said fluid and solvent vapour produced by the ink.The air blown by the said means of impulsion, which consist of animpulsion fan coupled to a conduit connected to the entrance to thedrying box 19, is previously heated, for example, by means of a fuelheater or an electric heating element.

It should be noted that the cited means of air impulsion and heating forthe drying boxes 19 are independent of the means of introducing 21 theair at regulated temperature which circulates through the sections. Onthe other hand, the means of circulation 8 are common. This is becausethe circulating air entry may require heating, but it might also requirecooling in function of the general operating conditions. Therefore, theintroduced air at the regulated temperature is heated/cooled by means ofsuitable means, such as a water-air heat exchanger 20 located outsidethe sections.

As an advantage, at least one temperature sensor is installed inside thesurrounding casing 6, together with the electronic means to control theoperation of the said heat exchanger 20, the blower fan 21 and theextraction fan 8 in order to regulate the flow rate and temperature ofthe entry fluid and the flow rate of the exit fluid and solvent vapourin function of a signal received from the said temperature sensor.According to a more complete variant, the printer of this inventionincludes several of the said temperature sensors installed at variouspoints of the said first, second and third sections 12 a, 12 b and 12 c,together with the means of inspection in various branches of the saidentry 13 and exit 14 conduits, the means of inspection of which aredriven by their respective drive means. Here, the said electronic meanscontrol the heat exchanger operation 20, the blower fan 21, extractionfan 8 and the cited drive means of the means of inspection in order toregulate the flow rate and the temperature of the entry fluid, togetherwith the exit flow rate of the fluid and solvent vapour at the variouszones of the first, second and third sections 12 a, 12 b and 12 c, infunction of the signals received from the said temperature sensors.

Although the invention has been described in relation to specificconstruction examples, these examples have a merely illustrativecharacter and do not limit the scope of this invention, which is definedin the following claims.

1. A flexographic printer with temperature-controlled sections andvapour extraction of the type comprising: a frame; at least one rotatingback-pressure cylinder, which is mounted on said frame, with an exteriorsupport surface for a band to be printed, at least one flexographic headcomprising: a cliché-holder that can come into contact with the band tobe printed over said back-pressure cylinder; and a print head comprisingat least one inking cylinder which supplies ink from a tank to saidcliché-holder cylinder; wherein the components of said flexographicprint head can be moved closer to or farther away from saidback-pressure cylinder, of which there is at least one; means ofrotating drive for said cylinders, of which there is at least one ofeach and means for movement drive for said at least one flexographicprint head; means of drying or curing a film of ink deposited on theband to be printed; and a surrounding casings, means of interiordivision which, in combination with said surrounding casing, delimit atleast one first and one second sections; and means of circulating fluidthrough said first and second sections, of which there are at least twoand at least one temperature-controlled fluid, with the first and secondsections being sufficiently closed and insulated from each other andproducing the cited fluid circulation at a flow rate that is sufficientto provide an atmosphere with a concentration of solvent vapour comingfrom the ink that is below a preset explosion limit in at least thesecond section, which contains electrical and/or electronic elementsand/or devices that are associated with said means of rotation andmovement drives.
 2. A printer in accordance with claim 1, wherein saidmeans of fluid circulation at a regulated temperature, comprises meansof introducing by impulsion and the means of extraction by suction, withrespective impulsion mouths and suction connections, located indifferentiated zones inside said surrounding casing.
 3. A printer inaccordance with claim 1, wherein all the means of drive and theassociated electrical and/or electronic elements and/or devices arearranged in the cited second section, of which there is at least one,which is separated and sufficiently insulated from the first section,which houses the cited back-pressure cylinders, cliché-holder and inker,together with said means of drying.
 4. A printer in accordance withclaim 3, wherein said frame comprises first and second supportstructures with their respective internal faces facing each other andbetween which are installed the back-pressure cylinders, cliché-holderand inker, together with the means of drying and respective externalfaces opposite said facing faces, with the means of division arranged inrelation to said first support structure in order to create said firstsection between the internal facing faces of the first and secondsupport structures and said second section in a zone adjacent to theexternal face of the first support structured.
 5. A printer inaccordance with claim 4, wherein said means of division are alsoarranged in relation to said support structure in order to create athird section in a zone adjacent to the external face of the secondsupport structure, in which the third section contains some of the drivemeans and/or the associated electrical and/or electronic elements and/ordevices, with said second and third sections flanked by the firstsection (12 a), which then intermediate.
 6. A printer in accordance withclaim 5, wherein the drive means include the means of guidance andmechanical transmission also located in said second and third sectionsand safeguarded from possible impregnation by ink, with said firstsection and the elements it contains easily accessible for cleaning. 7.A printer in accordance with claim 5, wherein said means of introducingthe fluid by impulsion comprises at least one fan connected to a fluidintroduction conduit, which is fitted with branches with severalimpulsion mouths distributed inside said first, second and thirdsections and because said means of fluid extraction by suction comprisesat least one fan connected to an exit conduit with branches with severalsuction connections distributed inside said first, second and thirdsections.
 8. A printer in accordance with claim 7, wherein said means ofdivision comprises fluid curtains that are blown from impulsion mouthsconnected to introduction conduit branches and located in relation tosaid first and second support structures in an upper zone inside thecasing and sucked from several suction connections, which are connectedto the exit conduit branches and located in relation to said first andsecond support structures in an lower zone inside the casing.
 9. Aprinter in accordance with claim 8, wherein said means of divisioncomprises at least one of elastic, flexible and/or sliding means tocover the apertures in the first and second support structures by meansof which the at least one flexographic print head moves.
 10. A printerin accordance with claim 7, wherein at least one of said suctionconnections are located in a lower section of each of the second andthird sections in order to extract solvent vapour coming from the ink,together with the exit fluid.
 11. A printer in accordance with claim 10,wherein said means of division comprises at least one elastic, flexibleand/or sliding means to cover the apertures in the first and secondsupport structures by means of which the at least one flexographic printhead moves.
 12. A printer in accordance with claim 7, wherein said meansof drying or curing comprises at least one drying box connected by oneside to the means of impulsion that blow a previously heated fluid overthe printed band and is connected at the other side to at least onebranch of the exit conduit connected to said means of suction in orderto suck said fluid and solvent vapour coming from the ink.
 13. A printerin accordance with claim 12, wherein said means of fluid impulsioncomprises a blower fan coupled to a conduit connected to a drying boxentry, with said fluid being previously heated by a means of heating.14. A printer in accordance with claim 13, wherein said means of heatingis one of a fuel burner or electric heating element.
 15. A printer inaccordance with claim 5, wherein said fluid that is introduced at aregulated temperature is heated/cooled a means of heating/cooling.
 16. Aprinter in accordance with claim 15, wherein said means ofheating/cooling is a water/air heat exchanger.
 17. A printer inaccordance with claim 16, further comprising at least one temperaturesensor located inside the surrounding casing and electronic means ofoperational control of said heat exchanger and/or blower fan and/orextraction fan in order to regulate the fluid entry temperature and theexit flow rate of the fluid and solvent vapour in function of a signalreceived from said temperature sensor.
 18. A printer in accordance withclaim 17, further comprising a plurality of said temperature sensors,located at various points of the first, second and third sections andthe means of inspection in various branches of said entry and/or exitconduits, with said means of inspection driven by their respective drivemeans, where said electronic means control the heat exchanger and/or theblower fan and/or the extraction fan and/or of the means of inspectionto regulate the flow rate and temperature of the entry fluid and theflow rate of the exit fluid and solvent vapour in the various zones ofthe first, second and third sections in function of the signals receivedfrom the temperature sensors.
 19. A printer in accordance with claim 1,wherein said circulating fluid is a gas.
 20. A printer in accordancewith claim 19, wherein said gas fluid is air.
 21. A printer inaccordance with claim 1 comprising a single, common back-pressurecylinder for various flexographic print heads being the temperature ofsaid unique back-pressure cylinder independently regulated by means of awater cooling device.
 22. A printer in accordance with claim 1comprising a plurality of flexographic print heads, each one beingassociated with a specific back-pressure cylinder.